12,370 research outputs found
Eight-fold signal amplification of a superconducting nanowire single-photon detector using a multiple-avalanche architecture
Superconducting nanowire avalanche single-photon detectors (SNAPs) with n
parallel nanowires are advantageous over single-nanowire detectors because
their output signal amplitude scales linearly with n. However, the SNAP
architecture has not been viably demonstrated for n > 4. To increase n for
larger signal amplification, we designed a multi-stage, successive-avalanche
architecture which used nanowires, connected via choke inductors in a
binary-tree layout. We demonstrated an avalanche detector with n = 8 parallel
nanowires and achieved eight-fold signal amplification, with a timing jitter of
54 ps.Comment: 7 pages, 3 figure
Remote capacitive sensing in two-dimension quantum-dot arrays
We investigate gate-defined quantum dots in silicon on insulator nanowire
field-effect transistors fabricated using a foundry-compatible fully-depleted
silicon-on-insulator (FD-SOI) process. A series of split gates wrapped over the
silicon nanowire naturally produces a bilinear array of quantum
dots along a single nanowire. We begin by studying the capacitive coupling of
quantum dots within such a 22 array, and then show how such couplings
can be extended across two parallel silicon nanowires coupled together by
shared, electrically isolated, 'floating' electrodes. With one quantum dot
operating as a single-electron-box sensor, the floating gate serves to enhance
the charge sensitivity range, enabling it to detect charge state transitions in
a separate silicon nanowire. By comparing measurements from multiple devices we
illustrate the impact of the floating gate by quantifying both the charge
sensitivity decay as a function of dot-sensor separation and configuration
within the dual-nanowire structure.Comment: 9 pages, 3 figures, 35 cites and supplementar
Stabilizing entanglement autonomously between two superconducting qubits
Quantum error-correction codes would protect an arbitrary state of a
multi-qubit register against decoherence-induced errors, but their
implementation is an outstanding challenge for the development of large-scale
quantum computers. A first step is to stabilize a non-equilibrium state of a
simple quantum system such as a qubit or a cavity mode in the presence of
decoherence. Several groups have recently accomplished this goal using
measurement-based feedback schemes. A next step is to prepare and stabilize a
state of a composite system. Here we demonstrate the stabilization of an
entangled Bell state of a quantum register of two superconducting qubits for an
arbitrary time. Our result is achieved by an autonomous feedback scheme which
combines continuous drives along with a specifically engineered coupling
between the two-qubit register and a dissipative reservoir. Similar autonomous
feedback techniques have recently been used for qubit reset and the
stabilization of a single qubit state, as well as for creating and stabilizing
states of multipartite quantum systems. Unlike conventional, measurement-based
schemes, an autonomous approach counter-intuitively uses engineered dissipation
to fight decoherence, obviating the need for a complicated external feedback
loop to correct errors, simplifying implementation. Instead the feedback loop
is built into the Hamiltonian such that the steady state of the system in the
presence of drives and dissipation is a Bell state, an essential building-block
state for quantum information processing. Such autonomous schemes, broadly
applicable to a variety of physical systems as demonstrated by a concurrent
publication with trapped ion qubits, will be an essential tool for the
implementation of quantum-error correction.Comment: 39 pages, 7 figure
High-Speed, Photon Counting CCD Cameras for Astronomy
The design of electron multiplying CCD cameras require a very different
approach from that appropriate for slow scan CCD operation. This paper
describes the main problems in using electron multiplying CCDs for high-speed,
photon counting applications in astronomy and how these may be substantially
overcome. With careful design it is possible to operate the E2V Technologies
L3CCDs at rates well in excess of that claimed by the manufacturer, and that
levels of clock induced charge dramatically lower than those experienced with
commercial cameras that need to operate at unity gain. Measurements of the
performance of the E2V Technologies CCD201 operating at 26 MHz will be
presented together with a guide to the effective reduction of clock induced
charge levels. Examples of astronomical results obtained with our cameras are
presented.Comment: 11 pages, 5 figure
High performances monolithic CMOS detectors for space applications
During the last 10 years, research about CMOS image sensors (also called APS -Active Pixel Sensors) has been intensively carried out, in order to offer an alternative to CCDs as image sensors. This is particularly the case for space applications as CMOS image sensors feature characteristics which are obviously of interest for flight hardware: parallel or semi-parallel architecture, on chip control and processing electronics, low power dissipation, high level ofradiation tolerance... Many image sensor companies, institutes and laboratories have demonstrated the compatibility of CMOS image sensors with consumer applications: micro-cameras, video-conferencing, digital-still cameras. And recent designs have shown that APS is getting closer to the CCD in terms ofperformance level. However, the large majority ofthe existing products do not offer the specific features which are required for many space applications. ASTRI1JM and SUPAERO/CIMI have decided to work together in view of developing CMOS image sensors dedicated to space business. After a brief presentation of the team organisation for space image sensor design and production, the latest results of a high performances 512x512 pixels CMOS device characterisation are presented with emphasis on the achieved electro-optical performance. Finally, the on going and short-term coming activities of the team are discussed
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